Hot-Wall Retort Furnaces up to 1100 °C

Bayonet quick-lock for the retort, also with electric drive as additional equipment

Parallel guided door to open the hot retort furnace as additional equipment

These gas tight retort furnaces are equipped with direct or indirect heating depending on temperature. They are perfectly suited for various heat treatment processes requiring a defined protective or a reaction gas atmosphere. These compact models can also be laid out for heat treatment under vacuum up to 600 °C. The furnace chamber consists of a gas tight retort with water cooling around the door to protect the special sealing. Equipped with the corresponding safety technology, retort furnaces are also suitable for applications under reaction gases, such as hydrogen or, in combination with the IDB package, for inert debinding or for pyrolysis processes.

Different model versions are available depending on the temperature range required for the process:

Models NRA ../06 with Tmax 650 °C

Heating elements located inside the retort

Temperature uniformity up to +/- 5 °C inside the work space

Retort made of 1.4571

Gas circulation fan in the back of the retort provides for optimal temperature uniformity

Models NRA ../09 with Tmax 950 °C

Outside heating with heating elements around the retort

Temperature uniformity up to +/- 5 °C inside the work space

Retort made of 1.4841

Fan in the back of the retort provides for optimal temperature uniformity

When a flammable process gas like hydrogen is used, the retort furnace is additionally equipped with the required safety technology. Only certified and industry proven safety sensors are used. The furnace is controlled by a fail-safe PLC control system (S7- 300F/safety controller).

IDB Version for Debinding under Non-flammable Protective Gases or for Pyrolysis Processes

The retort furnaces of the NR and NRA product line are perfectly suited for debinding under non-flammable protective gases or for pyrolysis processes. The IDB version of the retort furnaces implements a safety concept by controlled purging the furnace chamber with a protective gas. Exhaust gases are burned in an exhaust torch. Both the purging and the torch function are monitored to ensure a safe operation.

Process control under monitored and controlled overpressure of 50 mbar relative

Process control H1700 with PLC controls and graphic touch panel for data input

Cold-Wall Retort Furnaces up to 2400 °C or up to 3000 °C

Retort furnace SVHT 9/24-W with tungsten heating

Graphite heating module

Cylindrical retort with tungsten heating

Cooling water distribution

Compared with the VHT models (page 54 ff), the retort furnaces of the SVHT product line offer improved performance data with regard to achievable vacuum and maximum temperature. Due to the design as pit-type furnace with tungsten heating, processes up to max. 2400 °C even in high vacuum can be implemented with retort furnaces of the SVHT..-W product line. Retort furnaces of the SVHT..-GR product line with graphite heating, also in pit-type design, can be operated in an inert gas atmosphere even up to max. 3000 °C.

Standard sizes with a furnace chamber of 2 or 9 liters

Designed as pit-type furnace, charged from above

Frame construction with inserted sheets of textured stainless steel

Dual shell water-cooled stainless steel container

Manual operation of process gas and vacuum functions

Manual gas supply for non-combustible process gas

A step in front of the retort furnace for an ergonomic charging height

Retort lid with gas-charged shock absorbers

Controls and switchgear as well as gas supply integrated in furnace housing

Defined application within the constraints of the operating instructions

Heat treatment of copper bars under hydrogen in a retort furnace VHT 8/16-MO

The compact retort furnaces of the VHT product line are available as electrically heated chamber furnaces with graphite, molybdenum, tungsten or MoSi2 heating. A wide variety of heating designs as well as a complete range of accessories provide for optimal retort furnace configurations even for sophisticated applications.

The vacuum-tight retort allows heat treatment processes either in protective and reaction gas atmospheres or in a vacuum, subject to the individual furnace specs to 10-5 mbar. The basic furnace is suited for operation with non-flammable protective or reactive gases or under vacuum. The H2 version provides for operation under hydrogen or other flammable gases. Key of the specification up is a certified safety package providing for a safe operation at all times and triggers an appropriate emergency program in case of failure.

Alternative Heating Specifications

In general the following variants are available wit respect to the process requirements:

VHT ../..-GR with Graphite Insulation and Heating

Suitable for processes under protective and reaction gases or under vacuum

Tmax 1800 °C or 2200 °C (2400 °C as additional equipment)

Max. vacuum up to 10-4 mbar depending on pump type used

Graphite felt insulation

VHT ../..-MO or VHT ../..-W with Molybdenum or Tungsten Heating

Suitable for high-purity processes under protective and reaction gases or under high vacuum

Inner process box made of molybdenum, tungsten, graphite or CFC, especially recommended for debinding processes. The box is installed in the furnace with direct gas inlet and outlet and provides for better temperature uniformity. Generated exhaust gases will be directly lead out the inner process chamber during debinding. The change of gas inlet pathes after debinding results in a cleaned process gas atmosphere during sintering.

Charge thermocouple with display

Temperature measurement at 2200 °C models with pyrometer and thermocouple, type S with automatic pull-out device for precise control results in the low temperature range (VHT 40/..-GR and larger)

Two-stage rotary vane pump with ball valve for pre-evacuating and heat-treating in a fine vacuum (up to 10 2 mbar)

Turbo molecular pump with slide valve for pre-evacuation and for heat treatment in a high vacuum (up to 10 5 mbar) including electric pressure transducer and booster pump

Other vacuum pumps on request

Heat exchanger with closed-loop cooling water circuit

Automation package with process control H3700

12" graphic touch panel

Input of all process data like temperatures, heating rates, gas injection, vacuum at the touch panel

Two-stage rotary vane pump for heat treatment in a vacuum to 10-2 mbar

Turbo-molecular pump with booster pump for heat treatment in a vacuum to 10-5 mbar

H2 Version for Operation with Hydrogen or other Reaction Gases

In the H2 version the retort furnaces can be operated under hydrogen or other reaction gases. For these applications, the systems are additionally equipped with the required safety technology. Only certified and industry proven safety sensors are used. The retort furnaces are controlled by a fail-safe PLC control system (S7-300F/safety controller).

Certain processes require charges to be debinded in non-flammable protective or reactive gases. For these processes we fundamentally recommend a hot-wall retort furnace (see models NR… or SR…). These retort furnaces can ensure that the formation of condensation will be avoided as throughly as possible.

If there is no way to avoid the escape of small amounts of residual binder during the process, even in the VHT furnace, the retort furnace should be designed to meet this contingency.

The furnace chamber is equipped with an additional process box that has a direct outlet to the exhaust gas torch through which the exhaust gas can be directly vented. This system enables a substantial reduction in the amount of furnace chamber contamination caused by the exhaust gases generated during debinding.

Depending on the exhaust gas composition the exhaust gas line can be designed to include various options.